Question

Consider the following two-car accident: Two cars of equalmass
collide at an intersection. Driver E was traveling
eastward, anddriver N, northward. After the collision, the two cars
remainjoined together and slide, with locked wheels, before coming
torest. Police on the scene measure the length of the skid marks to be 9 meters. The coefficient
offriction between the locked wheels and the road is equal to 0.9.
Eachdriver claims that his speed was less than 14 meters per second
(50mph). A third driver, who was traveling closely behind driver
Eprior to the collision, supports driver E's claim by asserting
thatdriver E's speed could not have been greater than 12 meters
persecond. Take the following steps to decide whether driver
N'sstatement is consistent with the third driver's
contention.

Q. Let the speeds of drivers E and N prior to the collision
bedenoted by and , respectively. Find , the square of the speed of the two-car system
theinstant after the collision.

Express your answer terms
of and .

Q. What is the kinetic
energyof the two-car system immediately after the collision?